/* 初次进入页面时动画 */
.why-appear {
  transform: translateX(-150px);
}
.why-appear-active {
  transform: translateX(0);
  transition: transform ease 1s;
}

/* 进入动画 */
.why-enter {
  opacity: 0;
}

.why-enter-active {
  opacity: 1;
  transition: opacity ease 1s;
}

/* 离开动画 */
.why-exit {
  opacity: 1;
}

.why-exit-active {
  opacity: 0;
  transition: opacity ease 1s;
}